The present invention relates to an information reading device for reading a document on which image information consisting of characters and graphics are written or an information reading device for reading a document having character-and-graphic information on both surfaces and, more particularly, to an information reading device which is usable as a portable type information terminal.
Information reading devices each comprising a light source for illuminating a document, a photoelectric converter having series-arranged elements for receiving light from a light-source and converting the light into electric signals, scanning means for moving relative positions of the photoelectric converter and the document in the orthogonal directions and a data processing portion for transmitting a series of output electric signals from the photoelectric converter are widely applied in facsimiles, copying machines and so on.
Hand scanners which are used as connected to a personal computer, word processor or the like for reading thereinto a part of a sentence or printed matters; These are one-dimensional line-scanners which have a limited area of reading.
There has been proposed such a two-dimensional image reading device wherein photoelectric cells formed in two-dimensional matrix serves as light-sensitive elements for optically inputting manuscript information and graphic information into a computer. For example, Japanese Laid-Open Patent No. 60-262236 describes a coordinate input device of this type which, consists of a glass substrate, a sintered CdS (Cadmium Sulfide) layer formed in stripes on the glass substrate to work as electrodes for detecting a X-coordinate value and as a n-type semiconductor of a photoelectric cell, a layer of sintered CdTe (Cadmium Tellurium) formed in stripes at a right angle to the sintered CdS stripes and as p-type semiconductor of a photoelectric cell with nodes of the CdS stripes with sintered CdTe stripes being photoelectric cells and a carbon electrode layer formed over the sintered CdS layer to works as electrodes for detecting y-coordinate values and as a doping material to the sintered CdTe layer.
In a reference book "Sensor and signal processing," (2nd ed., 2nd print, Kyoritu Publishing Co., 1989, p. 170 et. seq.), there is described how to use a coordinate input device which is, by way of example, constructed by using photodiodes. As it will be explained later on referring to the figure, two-dimensional photodiodes are scanned first from an element (n, m)=(0, 0) to an element (0, 383), next from an element (1, 0) to an element (1, 383) and further are scanned in similar way to a last element (489, 383) to detect a photodiode which light enters. The device proposed in the cited material relates to a two-dimensional sensor portion.
As described above, the prior arts have proposed:
(1) a device for reading information by mechanically moving a document or a line sensor portion; and PA1 (2) a structure of a two-dimensional reading sensor. PA1 a sensor panel consisting of a plurality of photoelectric cells formed in a two-dimensional matrix; PA1 a light-source for illuminating a sheet of the original document tightly put on the sensor panel; PA1 a scanning portion for scanning a plurality of the photoelectric cells on the sensor panel; PA1 a current-to-voltage converting portion for converting a current signal, which is produced by the photoelectric cells when having received reflected light from the original document, into a voltage signal; PA1 an amplifier portion for amplifying an output of the current-to-voltage converting portion; PA1 a signal processing portion for reproducing image information consisting characters and/or graphics from a signal from the amplifier portion, PA1 wherein the two-dimensional matrix of the photoelectric cells of the sensor panel is formed of first-layer striped electrodes made of material having high transmissivity and formed on a transparent substrate, a striped amorphous silicone layer laid in the direction orthogonal to the first striped electrodes on the transparent substrate and second-layer striped electrodes made of material having a low transmissivity and formed over the striped amorphous-silicone layer and the photoelectric cells thus formed in two-dimensional matrix serve as light-sensitive elements for optically reading information. Image information consisting of characters and/or graphics is two-dimensionally read from a document placed on the sensor panel by electrically scanning a two-dimensional matrix of the photoelectric cells of the sensor panel. The device has no driving mechanism for mechanically moving the document or the sensor panel and requires only placing document on the sensor panel. The device can have a reduced size with a minimized thickness. Light from the light source passes through the first-layer electrodes having high transmissivity and a transparent substrate and strikes the document surface. Reflected light from the document surface passes through the transparent substrate and the first-layer electrodes and enters into photoelectric cells formed by an amorphous silicone layer sandwiched between the first-layer electrodes having a high transmissivity and the second-layer electrodes having low transmissivity. The device thus constructed can read image information at a high sensitivity. PA1 a first flat reading portion consisting of a first sensor panel including a plurality of photoelectric cells formed in a two-dimensional matrix, a first light-source for illuminating a surface of a document sheet and a first supporting member for fixing the first sensor panel together with the first light source; PA1 a second flat reading portion consisting of a second sensor panel including a plurality of photoelectric cells formed in a two-dimensional matrix, a second light-source for illuminating a surface of a document sheet and a second supporting member for fixing the second sensor panel together with the second light source; PA1 first scanning means for scanning a plurality of the photoelectric cells of the first sensor panel; PA1 second scanning means for scanning a plurality of the photoelectric cells of the second sensor panel; PA1 a processing control portion for reading information of the document from output signals of photoelectric cells by controlling the first scanning means and the second scanning means; PA1 wherein information is inputted from the document tightly attached each surface to the first sensor panel and the second sensor panel.
The conventional information reading device provided with scanning means for moving relative positions of a photoelectric converter and a document in the orthogonal directions and a data processing portion for transmitting a series of output electric signals from the photoelectric converter is widely applied in facsimiles, copying machines and so on. This device, however, has complicate construction because the need of mechanically moving the photoelectric converter or the document.
Hand scanners widely used as connected to a personal computer, word processor or the like for reading thereinto a part of a sentence or printed matters. These are one-dimensional line-scanners which, therefore, have a limited area of reading.
The coordinate input device for use in two-dimensional reading consists of a glass substrate with two layers--a CdS (Cadmium Sulfide) layer and a CdTe (Cadmium Tellurium) laid thereon to form orthogonal stripes. The glass substrate has of course a high luminous transmittance but two layers formed on the glass substrate are made of sintered cadmium having a very low luminous transmittance. Consequently, the image input device has a low luminous transmittance in the direction from the glass substrate to the photoelectric cells or from the photoelectric cells to the glass substrate. Furthermore, improving the transmittance may be accompanied by weakening the output signal. To avoid this, it is necessary to further revise how to minimize noise and amplify an output signal in the process of reproducing information. There have been still left many problems to be solved before the coordinate input devices can be put into practical use in or with portable information terminal devices.
Therefore, if the need of moving a document side or a reading sensor side can be eliminated, no driving mechanism is used and electrical two-dimensional reading system can be applied making it possible to read an entire surface of a document. Such a information reading device may bring excellent features and advantages when be applied in information processing devices. There has been a keen need for an information reading device having a very thin size, which is reliable to work, simple and easy to use. In view of the foregoing, the present invention was made to provide a two-dimensional information reading device which has no moving mechanism and can provide reliable input information.
Furthermore, the conventional information input (or reading) device which is provided with scanning means for moving position of photoelectric converter relative to a document in orthogonal directions and a data processing portion for transmitting a series of output electric signals from the photoelectric converter, is widely applied in facsimiles, copying machines and so on. This device, however, must mechanically move its photoelectric converter or a document therein. Therefore, it is not adapted to use as a portable input device.
When inputting information from both surfaces of a document by using the conventional device, one must turn over the document or move the photoelectric converter to the reverse side of the document. To input information on the reverse side of the document, it is needed to replace the document by hand or to use another device that has, besides its scanning mechanism, a mechanism for reversing a document, for example, mechanical turning-over system used in a two-sides copying machine. The latter includes a large-scale mechanical system and is bulky to carry.
Hand scanners widely used as connected to a personal computer, word processor or the like so as to input thereinto a part of a sentence or printed matters. These are one-dimensional line-scanners which, therefore, have a limited area of reading and must be manually scanned on one side of the document and manually replaced to the reverse side of the document.
Pocketbook or notebook type input devices are most desirable to carry. Japanese Laid-Open Utility Model No. 61-7160 proposes a notebook type information input device that is, however, unsuited to carry because of using a movable system of solid-state image sensors for image information inputting. Japanese Laid-Open Patent No. 3-209872 describes an information input device for detecting reflected light from a document by using two-dimensional light-receiving sensors, which, however, can not input information from both sides of the document.